Also check out the cool stuff introduced in Mac Mouse Fix 2!
The app works again.
I signed the app with a new certificate. The old certificate was revoked by Apple which renders old versions of Mac Mouse Fix unusable. See this post for more info.
New feature!
You can now control Media Playback, Speaker Volume, Display Brightness and more right from your mouse!
This is possible because Mac Mouse Fix now lets you remap your mouse buttons to any key on your keyboard - even Apple's proprietary function keys like "Play-Pause" or "Mute Speaker".